A Preliminary Evaluation of the Use of Gun Bluing to Enhance Friction Ridge Detail on Cartridge Casings

Friction ridge detail was enhanced on f ired and unfired 9 mm brass Luger ammunition casings using three techniques, two involving gun blue reagent at a concentration of 50% v/v. Fingermarks were deposited on 90 ammunition casings, and half were discharged using a Glock 19 semiautomatic pistol. Mark development was achieved using either superglue fuming followed by basic yellow 40 f luorescent dye staining (SG → BY40), superglue fuming followed by gun blue (SG → GB), or gun blue (GB) as a single process. All three processes developed ridge detail on both f ired and unfired casings. The results of this preliminary work show that the use of gun blue as a single enhancement technique was able to enhance ridge detail of the highest quality and clarity, particularly on f ired casings, making it the most effective process.